Okay, first of all straight grain wood expands very little longitudinally, but we aren't always dealing with that! Curly wood definitely doesn't follow this model and any pattern layed out such that the forestock is at a bias relative to thee the grain direction doesn't as well. This is absolutely not debatable. We see it all the time in our business. The amount of expansion or contraction can vary from next to nothing to probably 3/32" on an extreme case.
So, I would consider 1/16" on each side of the hole to be an absolute minimum amount of slotting for the pin closest to the muzzle. Moving towards the breech, they could be progressively less if you felt like thinking about that.
Rotary tools can work, but there is a risk. The risk is not allowing the slot to extend any further from the barrel than the original hole position. This isn't always easy. A jewelers say really isn't difficult. Just use a decent quality blade and let the say do the cutting. I'm sure I show this in some of our videos. Follow up with a needle file to true things up and your good to go. Insert a pin to make sure it's free to move in the slot and you're good to go.
Jim
So, I would consider 1/16" on each side of the hole to be an absolute minimum amount of slotting for the pin closest to the muzzle. Moving towards the breech, they could be progressively less if you felt like thinking about that.
Rotary tools can work, but there is a risk. The risk is not allowing the slot to extend any further from the barrel than the original hole position. This isn't always easy. A jewelers say really isn't difficult. Just use a decent quality blade and let the say do the cutting. I'm sure I show this in some of our videos. Follow up with a needle file to true things up and your good to go. Insert a pin to make sure it's free to move in the slot and you're good to go.
Jim
